BX 16 Valve Engine

XU9J4 (D6C) Engine

The majority of the BX 16v engines were the non cat version fitted with Motronic 4.1 engine management (2 row ecu) which is explained in detail in the Technical sub-pages. The later engines were fitted with the Motronic 1.3 management (3 row ecu) utilising a knock sensor mounted on the front of the engine block, this allows the ecu to adjust ignition timing if pinking occurs.

The cam pulleys are numbered and there seem to be several factory combinations – The most common variations seem to be the early engines using a #2 exhaust cam pulley and a #4 inlet cam pulley this later changed to a #2 cam pulley on both the inlet and exhaust cam. The combination of #2 and #4 seems to give the more harsh power delivery often noticed with the mi16 engine.

The engine is of all alloy construction utilising removeable cast iron cylinder liners.

XU9J4/Z (DFW) With Catalytic Converter

This is the cat equipped engine using the Motronic 1.3 engine management (3 row ecu) along with a lambda (oxygen) sensor and is essentially the same as the D6C apart from the details below.These differences are achieved using lower height pistons and the common cam pulley arrangement is a #3 inlet cam pulley with a #2 exhaust cam pulley. It appears that the #3 pulley was used to improve power delivery and help make up for the loss of power due to the cat and lower compression ratio.

Compression Ratio

9.7:1

Max Power

148BHP

Cam Pulleys

#2 – 114 deg
#3 – 111 deg

A drawing of a Citroen BX 61 Valve Engine

Engine

Model application

D6C (XU9J4)

Compression ratio

10.4:1

Maximum power DIN (BHP)

160 at 6500 rpm

Maximum torque DIN (lbf ft)

133 at 5000 rpm

Valves

Cam Pulleys

#2 – 114 deg
#3 – 111 deg
#4 – 108 deg

Head diameter:

Inlet

34.7 mm

Exhaust

29.7 mm

Cam followers

Hydraulic (no adjustment)

Valve Timing

Valve lift

9.2 mm

Inlet opens*

1º 35’ BTDC

Inlet closes*

45º 50’ ABDC

Exhaust opens*

47º 0’ BBDC

Exhaust closes*

0º 30’ ATDC

*With valve clearance of 1.0 mm

Crankshaft

Endfloat thrustwasher thicknesses

2.33 to 2.53 mm
(in increments of 0.05 mm)

Crank journal diameter

59.7 to 60.0 mm

Crankpin diameter

49.7 to 50.0 mm

Lubrication system

Oil pressure:

At 850 rpm

2.0 bar

At 3000 rpm

4.8 bar

At 6500 rpm

5.5 bar

Oil pressure warning lamp threshold

0.8 bar

Oil filter bypass threshold

1.2 bar

Maximum running oil temperatures

140 – 150 degrees C

Oil filter

Champion F104

Oil type (recommended)

SAE 10W40 or 15W40
(to API SG/CD standard)

Oil capacity (with filter change)

5.3 litres (9.3 pints)

Dipstick minimum to maximum

1.5 litres (2.6 pints)

Torque wrench settings Nm lbf ft

Camshaft bearing cap Allen screws

10 7

Main bearing cap bolts and nuts

50 37

Centre main bearing cap side bolts

25 18

Sump pan bolts

20 15

Big-end bearing cap nuts:

Stage 1

40 30

Stage 2: slacken, then tighten to

20 15

Stage 3: then immediately

Tighten a further 70º

Oil pump bolts

20 15

Flywheel bolts

50 37

Clutch cover bolts

25 18

Crankshaft sprocket bolt

110 82

Coolant pump bolts

15 11

Camshaft sprocket bolts

45 33

Timing belt tensioner locking screw

20 15

Engine mounting bracket at timing cover end:

Larger bolts

72 53

Smaller bolts

45 33

Crankshaft damper bolts

25 18

Camshaft rear pulley bolt

45 33

Inlet manifold bolts

20 15

Exhaust manifold bolts

25 18

Cylinder head bolts:

Stage 1

60 43

Stage 2: slacken, and then tighten each bolt in turn to

20 15

Stage 3: then immediately

Tighten a further 300º

General information

The D6C engine is fitted to the majority of UK BX 16 valve models and is a development of the 8v engine.

Introduced in July 1987, the essential difference is the 16 valve double overhead camshaft cylinder head, this head is based upon the legendary T16 cylinder head and spent 6 years in development alone.

The camshafts are driven by a toothed belt tensioned by two idler rollers.

The need for valve clearance adjustment is eliminated by the incorporation of hydraulic tappets (cam followers).

The pistons have been re-designed, with valve head recesses machined in the piston crown and the gudgeon pins are now of the “floating” type, secured by circlips in the piston.

The undersides of the pistons are cooled by oil jets located in lubrication pipes within the crankcase.
The crankshaft has lighter balancing counterweights with a damper fitted to the sprocket end.

Pressurised oil is supplied by an oil pump located within the sump pan, the pump being driven by chain from the crankshaft.

An oil to water heat exchanger is also fitted to which the disposable canister type oil filter is fitted.

Cylinder Head

Further details of the cylinder head are available in the Downloads section which features pages from the Technical Manuals.